Effect of homonuclear boron bonds in the adsorption of DNA nucleobases on boron nitride nanosheets

Abstract

Quantum-mechanics calculations were carried out within the density functional theory (DFT) scheme, to analyze the sorbate-sorbent interaction between DNA nucleobases (purines: guanine and adenine; pyrimidines: cytosine and thymine) and hexagonal boron nitride nanosheets (pristine and non-stoichiometric) in two phases: i) gas and ii) aqueous. The resulting molecular simulations for the pristine nanosheet indicate that the four molecular sorbates prefer to be oriented perpendicular and/or parallel respect to sorbent. This geometrical effect generates adsorption energies associated to non-covalent interactions (physisorption), being the preferential adsorption sites those of N atoms of the nanosheet. According to the calculated quantum descriptors, they exhibit low chemical reactivity and work function, as well as high polarity and semiconductor-like behavior. However, the homonuclear boron bonds in the nanosheet (negatively charged) induce a strong interaction, almost three times larger than pristine nanosheet in gas phase; except for cytosine, due to this is weakly adsorbed in both phases. Moreover, the chemical reactivity and work function are reduced, whereas its conductivity (energy LHgap) and polarity were increased, since the preferential interaction site is corresponding to a B atom. Since the magnetic behavior (1.0 bohr magneton) of BN nanosheet/rB is not altered, the nanosheets with homonuclear boron bonds might be used as potential drug delivery vehicles and sensors.